Septal Myectomy Outcomes — EECC MCQ

Correct answer: A — Surgical septal myectomy (the Morrow procedure) has >95% success for gradient reduction and excellent long-term outcomes at experienced centres (<1% operative mortality, >90% durable symptom improvement); it is the gold standard for drug-refractory obstructive HCM

Surgical septal myectomy (extended Morrow procedure) is the gold standard treatment for drug-refractory obstructive HCM. The 2023 ESC Cardiomyopathy Guidelines recommend myectomy at experienced centres (≥10-20 procedures/year) for: symptomatic patients (NYHA III-IV or recurrent exertional syncope) with LVOT gradient ≥50 mmHg at rest or with provocation, refractory to maximal medical therapy. Outcomes at experienced centres: (1) operative mortality <1% (vs ~5% at low-volume centres — strong volume-outcome relationship); (2) >90% gradient abolition; (3) >90% long-term symptom improvement; (4) excellent long-term survival (~99% at 10 years, comparable to age-matched general population). Concurrent procedures: anterior mitral leaflet plication (if SAM is the dominant mechanism), papillary muscle realignment, myectomy extension to the mid-ventricle if needed. Alternatives: ASA (Class IIa — higher heart block rate) and mavacamten (Class IIa — reduces gradient pharmacologically).

Reference: ESC (2023): Cardiomyopathies Guidelines